Compressed air economizer for fluidic controls



Sept. 10, 1968 G. N, LEVESQUE COMPRESSED AIR ECONOMIZER FOR FLUIDICCONTROLS Filed Dec.

FIG I U it d ees Pet 3,400,881 COMPRESSED AIR ECONOMIZER FOR l 1'FLUIDIC CONTROLS George Napoleon Levesque, Warwick, RI; assignor tBrown & Sharpe Manufacturing Company, North Kingstown, R.I., acorporation of Rhode Island p 1 Filed Dec. .15, 1966, Ser. No. 601,891 96 Claims. (Cl. 230-.-1)

ABSTRACT "or I U E 3,400,881 Patented Sept. 10, J 1968 ice (3-15p.s.i.g.) suitable for operating the several elements of the controlcircuit, additional filtered air being supplied, to the enclosure tomake up for lostair and tomaintainwithin the enclosure a slightlyaboveatrnospheric pressure to exclude outside contaminated air. Theseveral features of the invention consist also in the devices,combinations and arrangements of parts herein after described andclaimed which together with the alvantages to be obtained thereby willbe readily understood by one skilled in the art from the followingdescription taken in connection with the accompanying a The disclosureof the present invention comprises a plurality ,of fluidic controlelements having inlet and discharge apertures thereto, .a gasconfining-enclosure with, in which said fiuidic control elements arehoused including said discharge apertures, a lowpressuregaseousfluidpump connected between the enclosure and said, fluidic control elementsproviding-a circuit to withdraw from said disclosure and to supply afiltered compressed gaseous fluid to said fluidic control elements at apredetermined fluidic element operating pressure, and means forsupplying additionalfiltered compressed gaseous fluid to said circuit tomaintain a fluid pressure in said enclosure slightly above atmosphere. pr In one form of the invention additional filtered compressed gaseousfiuidis supplied directly .to the enclosure from an outside source atslightly above atmospheric pressure. 7 In another form ofv the inventionadditional filtered compressed gaseous fluid is supplied to said fiuidiccontrol elements at said operating pressure, and a restricted outlet isprovided from said enclosure for-exhausting filtered gaseous fluidtherefrom at slightly .above HIIIIQS: pheric pressure. p

The present application relates, to a compressed air economizer forfiuidic controls.

A conventional fiuidic control system of the general type hereinreferred to for use in an automatic. machine tool may be of the wallattachment type comprising,by way of example, one hundred or more or-norand flipflop gates each operated by compressedflair supplied at alo woperating pressure which is normally held below p.s.i.,The compressedair for operatingthe several fluidic devices is conveniently suppliedfronna shop com pressed air line which may be. regulated to about 90pls.i. For use in a fluidic control panel the compressed air from theshop line is-filteredto eliminate water and oil, and is passed through areducing valve in orderto reduce the air pressure entering thefluidic'control .panel to the desired low pressure in the order of 15p.s.i.g. I

, While the amount of air required by any single or-nor or flip-flopgate is relatively small, amounting to about 17 standard cubic feet perminute (17 s.c.f.m'.) it will be appreciated that a fiuidic systememploying 100 such devices will, if all of the filtered air is lost,consume about 17 s.'c.f.m. requiring a compressor having a capacity ofseveral horsepower of the 90 psi. compressor capacity.

It is a principal object of the invention to provide a fiuidic controlsystem of the general" type above 'dedrawings in which: I p

FIG. 1 is a perspective view of a fluidic control panel mounted within asubstantially air tight enclosure to which compressed air is suppliedwhich is filtered and regulated to slightly above atmospheric pressureand an air pumpby means of which filtered air from the, enclosure israised to a suitable operating pressure in the order .of 3 to 15 psig.to the several devices within the panelat the desired operatingpressure, a portion of the enclosure being broken away to showunderlying parts including .a flip-flop and an or-nor gate connected tooperate a pilot valve and a reversible piston; and

FIG. 2 is a somewhat fragmentary perspective view of the fluidic controlpanel shown in FIG. 1 modified to include an air motor and an air pumpconnected to withdraw filtered air from the enclosure and to add suchadditional filtered air as may be required from supply at the desiredoperating pressure to the several devices within the panel, and apressure control air outlet from said enclosure.

Referring specifically to the drawings, the invention is illustrated asembodied in a fiuidic control system suitable for controlling a machinetool. It is contemplated that a fluidic control system of the generaltype referred to may have as many as 100 or-nor and flip-flop gates,which are utilized to control the automatic operation of the machine.FIG. 1 illustrates one example of a bi-stable flip-flop gate and acompanion mono-stable or-nor gate coupled to control the operation of asuitable pilot valve which directs the flow of a psi. compressed airline into one of two alternative channels to determine the direction ofmovement of a hydraulic piston. It will be understood that this controlsequence is illustrated as an example of the many such controls whichmay be found in a complex fluidic control system suitable forcontrolling the operation of a machine tool. The illustrated panel maybe built up of a plurality of separated layers having etched therein asubstantial number of such or-nor and flip-flop gates.

In the embodiment of FIG. 1 there is provided a. fluidic block or panel10 made up in the usual manner of successive layers of a suitable glassor similar material, which are cemented together, said layers, notspecifically shown, having etched therein the desired arrangement ofgates, resistors and connecting passageways. In the illustratedembodiments of the invention the panel 10 is mounted in an enclosure 12which is broken away to disclose the underlying panel 10. Two wallattachment devices are shown in dotted lines in the panel 10 including abi-stable flip-flop gate 14 and a mono-stable or-nor gate 16, which areconnected in a control sequence with a fiuidic gate controlled pilotvalve 18 to determine the direction of drive of a piston 20. Theflip-flop gate 14 of FIG. 1 comprises a main passageway 22 which isconnected with an inlet-supply line 23, and is formed with two forks 24,26, two control jet. passageways 28, 30 opening into the base of theforks at opposite sides thereof, and vents 32, 34 for the control jets.The fork 26 of the flip-flop gate is connected by a pipe 36 with one oftwo control inlet passageways 37 of the or-nor gate 16 which issimilarly formed with a main passage- 38 connected with the inlet supplyline 23 and having two forks 40, 42 the two control inlet jetpassageways 37 entering from the left side of the gate as shown, anexhaust connection 43 for the control jets 37 and an-additional smallexhaust connection in each fork.

The'or-nor gate 16, which is mono-stable, has a normal bias to the left,so that the operating pressure introduced through the main passageway 38is normally directed into the fork'40. However, when operating pressureis directed through pipe 36 and the control inlet passageway 37 theoperating pressure from the main passageway 38 is diverted into the fork42. i The control jet passageways 28, 30 of the flip-flop gaterecirculated as. needed. vTo

7 this end thewfluidic control system, comprising the control panel 10and the enclosed or-nor and flip-flop elements, is confined within theenclosure 12, which is maintained at slightly above atmospheric pressureto prevent contamination of the filtered air contained in saidfiuidicsystem, and a large percentage of this filtered air is collected andrecirculated, thus reducing the amount of such air used by the system byas much as-75%. Y I

In the embodiment of the invention shown in FIG. 1 the enclosure 12is'madepsubstantially air-tight. Compressed air is supplied from theconventional 90 p.s.i.g.

, shop line 60 to a conventional filter 72 which filters and 14 are fedfrom the supply line 23 through resistors 29,

31 which supply a control pressure to said control jet passages in theorder of 1.5 p.s.i. The flip-flop gate 14 is actuated by means of twopush buttons designated at Rt. 'and Lt. respectively. The Rt. pushbutton when pressed closes the open upper end of the control jetpassageway 30 causing the 1.5 p.s.i. control pressure therein to bedirected against the operating pressure which is diverted into the. lefthand fork 24. In the illustration shown this pressure is vented toexhaust. Pressing the Lt. push button closes the open end of an upwardextension of control passageway 28 causing a control pressure of 1.5p.s.i. to be directed against the stream of operating pressure from theleft diverting same into the right hand fork 26, and thence through thepipe 36 to the connected control inlet passageway 37 of the or-nor gate16 which causes the operating air pressure through the main channel tobe diverted into the right hand fork 42.

By way of example the flip-flop gate 14 and or-nor gate 16 are connectedto a fluid logic power amplifier which is the pilot valve above referredto. The pilot valve 18 comprises a housing within which is mounted avalve body 56 rotatably supported in a cylindrical aperture, and apiston 58 having its axis disposed at right angles to that of the valvebody 56. The piston, mounted in a cylinder 59, is grooved to engage anupward extension of the valve body 56, so that an axial shift of thepiston will rock the valve body 56 from one to an alternative operativeposition. A 90 p.s.i.g. compressed air supply line 60 introduced alongthe axis of the valve body 56 is delivered through a radial conduittherein to one of the two alternative pressure outlets 62, 64 from thevalve, acting through suitable connections to drive the piston 20mounted in a cylinder 68 alternatively in opposite dries theTair, thenpasses through-a pressure regulator 74 which is set to provide filteredair through a pipe 76 to the enclosure 12 at a pressure of .072' p.s.i.above atmosphere. Filtered air'at a pressure of about 15 p.s.i.

. issupplied to the "several fiuidic devices within the paneldirections.The air pressure from the exhaust end of the cylinder 68 is exhausted toatmosphere through exhaust ports in the housing of pilot valve 18. Itwill be noted that the filtered compressed air supplied through forks 40and 42 to the pilot valve 18 is eventually discharged into the enclosure12 and is thus conserved for reuse. Specifically, when filteredcompressed air is supplied through fork 40 to the cylinder 59 to movethe pilot valve body to the right, filtered air previously supplied tothe right hand end of the piston 58 is exhausted through fork 42 and theexhaust connection therein into the enclosure. Alternatively whenoperating pressure is applied through the fork 42 to move the pilotvalve body to the left filtered air is exhausted from the left hand endof the piston assembly through fork 40 and its associated exhaustconnection into the enclosure 12.

Under normal operating conditions in which the various exhaust openingsin the panel for both operating pressure and control pressureconnections are vented to atmosphere there is a substantial loss offiltered air which as above noted amounts to approximately (.17s.c.f.m.) .17 standard cubic feet per minute for each of the fluidicdevices contained in the panel.

In accordance with the invention provision is made for conserving andfor recirculating as large a percentage as possible of the filtered airsupplied to the panel with through line 23 by means of an air pump 78driven by an electric motor 80, which air pump draws filtered exhaustair fromthe' enclosure 12 through a conduit 82, raises the pressureofsaidair to the required level' of about 15 p.s.i. and directs saidrecompressed air to the several fiuidic devices through the inlet pipe23. While some of the filtered air supplied to the fiuidic devices islost, as for example, the control pressure supplied to the Lt. and Rt.push buttons above described, which are located outside the enclosure12, it will be appreciated that the major portion of the compressed airemployed to'operate the flip-flop and or-nor gates is vented within theenclosure 12 and is subsequently returned to the air pump 78 where it iscompressed to the required 15 psi. and returned to the panel 10 throughsupply pipe 23.

FIG. 2 illustrate an alternative arrangement of the fiuidic elementcontrol panel, including means for supplying filtered air at the desiredoperating pressure to the fiuidic elements contained within said panel,and enclosure 12 for said panel, means for drawing ofi and recirculatingfiiltered air vented from said fiuidic elements into the enclosure, anda vent 83 through the enclosure for venting a small'amount of saidfiltered air to atmosphere, the vent to atmosphere being gauged tomaintain a small internal pressure in the order of 2 inches of water or.072 psi. within the enclosure.

In the disclosure of FIG. 2 compressed air from a shop line, which may,for example, be 90 p.s.i.g. is passed through a variable throttle valve84, through the filter 72 to an air motor 86 which drives an airrecirculating pump 88 which draws filtered air from the enclosure 12 andfeeds it to the operating pressure supply line 23 of the panel unit. Airfrom the exhaust side of air motor 86 is combined with theair from theoutput side of the air pump 88 to supply the operating pressure supplyline 23. In this form of the invention the amount of filtered air whichcan be captured and recirculated is reduced by the amount of anyfiltered air loss through push buttons such as those above described andother controls using compressed air which are necessarily locatedoutside the enclosure 81, and additionally the filtered air which isdischarged through the vent 83 from the enclosure-12.

The modification shown in FIG. 2 also may be expected toeifectsubstantial savings of the filtered air supplied to the enclosedpanel 10. The loss offiltered air is limited to only that amount of suchfiltered air required by the air motor 86 to drive the air pump 88, inaddition to the other relatively small losses above noted. As in thefirst described embodiment of the invention .a saving of filtered airwhich would ordinarily be lost in the order of may be expected, therebysubstantially decreasing the size of compressor required for the 90p.s.i.g. line by the several horsepower, which 'would otherwise benecessary for supplying compressed air to the control panel.

While for convenience of illustration the several pump and motor unitsfor supplying filtered compressed air to the fiuidic control panel havebeen illustrated as located externally of the enclosure 12 it will beunderstood that these elements may equally well be mounted internally ofthe enclosure without changing in any way the operation of the apparatusherein described for economizing as to the amount of filtered air usedby the apparatus.

It is appreciated that provision 'has been made in the prior art forsupplying filtered air to enclosed areas in which a slightly aboveatmospheric pressure is maintained to exclude the entry of contaminatedair. Such pressurized areas are known as clean rooms. However, so far asthe applicant is aware the filtered air supplied to a clean room has notbeen further pressurized to do useful work, as is the case withapplicants enclosed fluidic control panel.

It will be understood that the invention in its broader aspects is notlimited to the two embodiments shown, and that the invention may takeother forms within the scope and spirit of the appended claims.

The invention having been described, what is claimed is:

1. Compressed gaseous fluid economizer for a fluidic control circuithaving, in combination with a plurality of fluidic control elementshaving inlet and discharge apertures thereto,

a gas confining enclosure within which said fluidic control elements arehoused including said discharge apertures,

a low pressure gaseous fluid pump connected between the enclosure andsaid fluidic elements providing a circuit to withdraw from saidenclosure and to supply a filtered compressed gaseous fluid to saidfluidic control elements at a predetermined fluidic element operatinggaseous pressure, and

means for supplying additional filtered compressed gaseous fluid to saidcircuit to maintain a fluid pressure in said enclosure slightly aboveatmosphere.

2. The combination of Claim 1, in which the com pressed gaseous fluid iscompressed air.

3. The combination of claim 2, in which said means for supplyingadditional fiiltered compressed air to said circuit comprises a sourceof high pressure compressed air, and an air filter, and a regulatingvalve connecting said source of high pressure compressed air into saidcircuit.

4. The combination of claim 3, in which the air filter and regulatingvalve are connected between the source of high pressure compressed airand said enclosure for supplying filtered compressed air to saidenclosure at slightly above atmospheric pressure.

5. The combination of claim 3, in which a vent is provided from saidenclosure sized to exhaust air therefrom at slightly above atmosphericpressure, and said filter and regulating valve are connected with theoutput side of said pump to supply added fiiltered compressed air intosaid circuit at said operating pressure.

6. The combination of claim 5, in which an air motor is connected todrive said pump, and the filtered and regulated compressed air from saidsource of high pressure compressed air is first applied to drive saidair motor, and is then mixed with the output from said pump to supplyfiiltered compressed air to said fluidic elements at said fluidicelement operating pressure.

References Cited UNITED STATES PATENTS 2,856,222 10/1958 Gossett et al.60-62 HENRY F. RADUAZO, Primary Examiner.

